Can I change the upstream O2 sensor without replacing the converter gasket?

Hello DAVENOOB,

You're welcome. Honestly the newer they are the worse they get. I will never buy a new car again. I would rather it be simple than all this electronic stuff. It can be very frustrating. I rewired an entire 72 Nova in 2 weeks, cars these days you pull apart one harness and there is over 30 circuits in it. It is not ideal.

It seems like it is having some kind of issue affecting the fuel/air ratio causing drivability issues. However, without a scan tool to look at what the computer is recording, I think the best thing to do is go with the one code we have and see what is going on there.

It is possible to have an issue with something like the O2 Sensor and not have a code, if the conditions for the code to be set hasn't been met. Things like the fault needs to happen for a certain amount of time, with the engine at or above a certain temperature, while it is in drive or things along those lines. All codes have different conditions for setting the DTC or Diagnostic Trouble Code.

This doesn't mean there isn't a problem in that area, it means the computer hasn't caught it yet.

Also, some codes can be current, others can be pending, and others can be history codes. It depends on the scan tool or code reader whether you get any codes but current or not.

However, something like an O2 sensor is Emissions related, so these codes usually show up very quickly if there is a problem and don't have a lot of parameters, they need to meet for the PCM to set the code.

It is possible for the EVAP system to cause drivability issues, so I think figuring out what is going on with that code and getting it fixed, should be our first priority.

Once that is out of the way, we can see how it is running and go from there.

Could be worse we could have ten codes and have to sift through all of those, lol.

My thought is if the valve is closed constantly, it would cause you to not be able to just fill it with gas without the pump shutting off. My 2003 Blazer did this to me. Loved that truck. Took me like 15 minutes to fill the tank. Had a vent valve code, switched out the valve and finally after years of dealing with it, problem was gone. After working on other cars all day, the last thing, I wanted to do is work on my own, that's the only reason I dealt with it for so long.

But since a wiring issue is a possibility and you will have a multimeter, we can test the wiring and the valve safely. We will skip running a jumper wire for now. The valves tend to get dirt in them, so GM redesigned them because they were getting water in them.

So, I will get some tests together for you and we will just make sure it is the valve, so we don't replace it prematurely. If it isn't we will check the signals coming in.

Thank you,
Brendon

Hello DAVENOOB,

What was the vehicle temperature? Was it warmed up fully? Also, what is the temperature outside?

Thank you,
Brendon

Hello DAVENOOB,

Also, when under heavy acceleration, like getting on the highway, the purge solenoid under the hood will not be open. Usually, it is open when the engine is up to temp and cruising at part throttle, so I think we are in the right area.

Here is the first test:

So, on the connector for the vent valve there should be a WHITE wire and a RED wire with a WHITE stripe or tracer.

WHITE-Solenoid Control- This is a ground wire that is switched in the PCM using something called a driver. A driver is simply an internal switch in the PCM. When the valve needs to be energized, the PCM simply just completes the ground also called the control.

RED/WHITE Stripe-Battery Positive-Should have 12 volts with key on engine off.

Place meter on second up from lowest setting on DC voltage. Should say 30 or 40. The symbol for DC is a straight line above a dashed or dotted line.

So, we will do this first. Let's make sure we are getting battery voltage at the valve:

1) Unplug the connector at the vent valve:
-Turn ignition key on with engine off
-Take BLACK lead and touch to ground, the frame is fine. You might have to scrape it to get a good connection.
-Then touch RED lead to the terminal the RED wire with the WHITE stripe on it.

You shou see 12 volts or close to it.

Note results.

Next:

1) Put meter on lowest setting for DC Voltage. Putting it on the lowest setting will give us milli-volts.

2)With the connector still unplugged:
-Touch the RED lead to the terminal for the WHITE wire.
-Then take BLACK lead and touch the frame again for ground.

You should see 0.1 volts which is one millivolt and is considered a good ground.

The PCM will connect this to close the valve and let the tank build pressure/vacuum to test the system.

Note results.

Let me know what you find, and we can take it from there.

Also let me know if I can clarify anything, sometimes I am not the best at explaining things.

Thank you,
Brendon

Hello DAVENOOB,

It doesn't need to be auto-ranging. The auto-ranging ones will have a switch that says "Range" so you can manually adjust it.

I think the one you sent me should be good enough.

The auto-ranging is a nice feature, so you don't have to keep switching it yourself, but it is not necessary. The cheaper ones normally don't have that feature.

You can always upgrade down the road.

You can keep driving it around if you would like. The more data the better. It sounds like the torque converter is stuck in lock-up. However, if the engine isn't running right, it will cause transmission issues.

The best thing to do in my opinion is to get the multimeter and let's see if we can get this vent valve issue fixed. Then we can see how it runs and go from there.

If it were my vehicle that is where I would start.

Thank you,
Brendon

Hello DAVENOOB,

Looks good from what I can see, let's hope it is decent. First thing you are going to want to do is put black lead into "COM" and the red lead in the middle hole.

Then set the meter on ohms, looks like a horseshoe kind of and try setting it at the "200" scale.

Now touch the 2 leads together and see if there is a reading. It should be zero or close to it.

Let me know if it isn't or you get OL or an I.

If it checks out good. Then set to DCV on 20. Now test the battery and verify you have 12 volts or close to it.

If so, then you can start testing for power at the connector for the vent valve.

Also visually inspect the wiring and the connector for any damage or corrosion.

Here is a good article about what to look for when checking wiring.
https://www.2carpros.com/articles/how-to-check-wiring

I have already added the tests for you but let me know if you can't find them and I will resend them.

Let me know if you need any help.

Thank you,
Brendon

Hello DAVENOOB,

Ohms seems high. Leads could have some resistance in them. Did you measure 12.43 at the battery or at the connector for the vent valve?

Thank you,
Brendon

Hello DAVENOOB,

Sorry just read it again. Sounds like it was the battery. Now unplug the connector on the vent valve and see if it has power with the key on engine off on the red wire with white tracer/stripe.

You should have close to the same that the battery had, 12 volts.

Thank you,
Brendon

Hello DAVENOOB,

So right now, you are on 5 amps. Move the switch around the opposite way and put on 20 DCV. The dot is like your arrow.

That should be max 20 volts.

It's ok. I am here to help. This is why I recommend the auto-ranging instead of the manual ranging. But it is alright, there will just be a little learning curve. No biggie. We will get it.

Thank you,
Brendon

Hello DAVENOOB,

No problem. Don't worry about it. When you say red lever do you mean for the connector?

Like this? (See image)

If you can, take a picture for me.

Thank you,
Brendon

Hello DAVENOOB,

Try some WD40 or PB Blaster if you have it. Brake clean will work too. Dirt is probably lodged in the keeping you from pulling it out. It might only come out a little and then from what I can see you can push on this tab to see image.

A pic or small flat head screwdriver will help as well.

Because of its location, it collects a lot of dirt so soaking it in some kind of oil will help a lot.

What do you have on hand for oils and cleaners?

If nothing, I know this sounds odd, but a couple drops of olive oil might help if you have nothing else. Put a drop at a time on your finger and let it soak into the connector.

Worst case sometimes the red lock will come out in pieces unfortunately. Not a big deal though the lock isn't necessary.

Thank you,
Brendon